Well, 'Densha Otoko' isn't real. It's more like a made-up tale that captured people's imaginations. The characters and events were crafted for entertainment.
Leo would likely take charge immediately. He'd assess the situation and start giving orders on how to help Mikey. He'd be calm on the outside but worried on the inside.
Their relationship in the fanfiction is likely to be full of mutual understanding. Since they are getting married, they must have a deep connection. Takato might be the more gentle and patient one, while Rika could be the strong - willed partner. They balance each other out.
Mikey might be a character created to tell a story about Pop Rocks. He could be a fictional child used to illustrate the appeal or novelty of these candies. For example, he could be a curious and adventurous little boy who wasn't afraid to try new things, like Pop Rocks, which were quite different from other candies at the time.
Leo would probably take charge immediately. He'd be focused on getting Mikey to safety and finding a way to treat his injuries. He might be blaming himself a bit for not being there to protect Mikey better.
In many fanfictions, Mikey is the optimist. He looks at the world with a positive outlook and tries to find the good in Rahzar. His friendly nature makes it easier for him to approach Rahzar, even though Rahzar might seem intimidating at first. Rahzar is usually depicted as having a lot of strength and power. He's a force to be reckoned with, but his character can also be complex, with hidden emotions that Mikey helps him uncover.
The 'densha otoko real story' is about a man's experiences on the train. It might involve his daily commute, the people he meets on the train, and the events that occur during his train rides.
April and Casey might also be part of this fanfiction. April could use her reporting skills to try and figure out what's going on with Mikey's mutation, and Casey would be ready to fight any new threats that come along because of Mikey's changed state. Also, Splinter, as their sensei, would be guiding them all through this difficult time, providing wisdom and training to help Mikey control his new powers if he has any.